In a current Long Term Evolution (LTE) system, user equipment (UE) synchronizes with an evolved NodeB (eNB) by detecting a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) that are sent by an evolved NodeB (eNB), user equipment (UE) synchronizes with the eNB and recognizes a physical cell. Then, the UE reads a system broadcast message sent by the eNB, initiates random access to the eNB, and finally can establish a radio resource control (RRC) connection to the eNB, so that the UE can perform data communication with the eNB.
The UE in RRC_CONNECTED mode needs to perform necessary measurement and synchronization tracking to perform data communication with the eNB. For example, the UE needs to measure channel state information (CSI) by using a cell-specific reference signal (CRS) or a channel state information-reference signal (CSI-RS), so that the eNB selects a suitable modulation and coding scheme for data scheduling of the UE. For another example, the UE needs to perform synchronization tracking, that is, fine time and frequency synchronization, by using the CRS, to ensure demodulation performance of data. Still for another example, the UE further needs to perform radio resource management (RRM) measurement by using the CRS, to ensure mobility performance of the UE.
However, in the prior art, user equipment cannot know which downlink subframes are used by a base station to transmit a CRS, and therefore, performance of communication between the user equipment and the base station is severely affected.